1. Field of Invention
The present invention relates to a tape carrier and a tape carrier device that mounts a semiconductor chip (IC) thereon.
2. Description of Related Art
A semiconductor apparatus is typically formed in the following manner. A semiconductor device is attached to a die pad that is mounted on a lead frame. External electrodes of the semiconductor device and terminals of the lead frame are connected by wires. This structure is packaged by thermosetting resin such as epoxy resin, and then the terminals are cut.
In recent years, electronic apparatuses have been further miniaturized and become thinner. Since semiconductor apparatuses used for these electronic apparatuses are mounted with a higher density, thinner and smaller semiconductor apparatuses are required. To meet such requirements, particular semiconductor apparatuses (tape carrier devices) are used. Typically, a semiconductor chip (IC) is disposed in a device hole defined in a film carrier such as a polyimide film, electrodes of the semiconductor device and inner leads of the carrier film are directly connected to one another, then this structure is printed or potted with a sealing material of liquid resin (for example, epoxy resin).
Conventionally, liquid epoxy resin, such as, for example, Chip Coat 8118 by Namix, Panasealer CV5755 by Matsushita Electronic Co., Ltd., and the like has been used as the sealing material. In the recent miniaturization of the external size of tape carrier devices, a resin sealing region becomes relatively large due to flowing of applied liquid resin with respect to the external size of a tape carrier. As a result, further miniaturization of the size of tape carrier devices is hindered.
A typical conventional tape carrier and a tape carrier device that mounts a semiconductor chip are shown in FIGS. 6A and 6B, respectively. In the figures, reference numeral 7 denotes a device hole, reference numeral 3 denotes an insulating film (base film), reference numeral 8 denotes a copper foil pattern, reference numeral 9 denotes a solder resist for pattern over coat, reference numeral 10 denotes outer leads, reference numeral 2 denotes inner leads, and reference numeral 6 denotes sealing resin for a semiconductor chip.
FIGS. 6A and 6B show a tape carrier for a liquid crystal driver. After the inner leads 2 overhanging on the device hole 7 and electrodes of an IC (semiconductor chip) are connected to one another, the connecting section, a circuit forming surface and a side surface of the semiconductor chip, a gap between the edge of the semiconductor chip and the edge of the device hole and an area outwardly extending from the device hole edge to the tape carrier by about 1.5 mm are covered by, typically, epoxy IC sealing resin 6.
The flow range of the sealing resin 6 is difficult to control because the resin is in the liquid form. In particular, sealing resin printed or dispensed on the tape upper surface flows through the gap between the edge of the semiconductor chip and the edge of the device hole to the rear surface side of the tape. The flow amount thereof is determined by various factors, such as the gap size between the edge of the semiconductor chip and the edge of the device hole which is the most significant factor, coating pressure from above, weight of the resin, viscosity of the resin, capillarity, surface tension of the resin and the like. Therefore, it is extremely difficult to control to restrict the flow amount of the resin and the expansion of the sealing range accompanied with the flowing resin. Accordingly, in the conventional products, a resin flow range outwardly extending from the edge of the device hole to an area on the tape carrier needs to be about 1.5 mm, and it is very difficult to reduce the resin flow range to a smaller value. However, with the reduction of the size of recent tape carrier devices, an occupancy ratio of a resin sealing range has become relatively large with respect the entire size of a tape carrier device, and this limitation of the resin sealing range causes problems such as hinderance of a further reduction of the tape carrier size.
Also, the device hole 7 of the above-described conventional tape carrier device has a configuration shown in FIGS. 7A-7C. FIG. 7A is an expanded view of an area adjacent the device hole, FIG. 7B is a cross-sectional view of one example taken along lines VII--VII of FIG. 7A, and FIG. 7C is a cross-sectional view of another example taken along the same lines VII--VII. In FIGS. 7A-7C, reference numeral 1 denotes a semiconductor chip, reference numeral 2 denotes inner leads, reference numeral 3 denotes a base film, reference numeral 5 denotes a remaining area of the area of the device hole after a semiconductor chip is mounted, which is also a resin passing area through which sealing resin flows to the rear surface side of the tape, and reference numeral 6 denotes a sealing resin.
In the case of the above-described conventional examples, in an area where the pitch of the inner leads 2 is relatively large, the remaining area 5 in the area of the device hole 7 that is left after a semiconductor chip is mounted is very large, and therefore a large amount of the sealing resin 6 flows around to the rear surface side of the base film (tape) 3. As a result, the range of the sealing resin on the rear surface side of the tape becomes larger. Consequently, the mold range has to be set at about 1.5 mm from the edge (end face) of the device hole 7 to a point on the film carrier outside of the edge. If a large amount of the resin flows, as shown in FIG. 7C, the sealing resin 6 may reach the rear surface of the semiconductor chip 1. Control of the sealing range is very difficult and substantially unstable because the resin 6 is in the liquid state. As a result of tests on 20 conventional examples, an average value of sealing ranges on the rear side surface of the tape was 1.2 mm, and the standard deviation of the sealing ranges was 0.2 mm.
Furthermore, even in a tape carrier of the conventional size, the number of terminals at the input side and the number of terminals at the output side of a semiconductor chip for a liquid crystal driver are different from each other. Moreover, when a semiconductor chip has a set of input terminals disposed on one side and a set of output terminals disposed on the opposite side due to the limitation of the circuit, the distance between adjacent terminals on the input side is substantially greater than the distance between adjacent terminals on the output side. As a result, a greater amount of sealing resin flows to the rear surface of the tape at the input side where the terminal-to-terminal distance is greater. To compensate for the resultant thinner sealing resin thickness on the upper surface, a greater amount of sealing resin needs to be coated. As a result, various problems occur. For example, the sealing range expands, and an excessive amount of sealing resin flows to the rear surface of the tape.